Emergency situations are best handled by personnel skilled in competent procedures that have been acquired through experience and training. The best insurance is good preparation.
Many emergencies require that the responding personnel be provided breathing apparatus to cope with toxic environments. Fires, chemical leaks, explosive atmospheres and underground operations are obvious, critical environments where breathing assistance is needed. In such cases the operator must be confident in the apparatus and his own ability to operate it safely and effectively. Otherwise, his attention to the task at hand will suffer in the emergency.
For perfect realism, the apparatus itself would be used in training. Inasmuch as containers of oxygen are used with oxygen breathing apparatuses, cost becomes a significant factor, however, and therefore simulation is encouraged. Accordingly, the next best thing to the perfect realism of the apparatus itself is the apparatus, slightly modified for training. That is what the present invention provides, with an insignificant loss in realism.
The prior art is devoid of any teaching that pertains to the simulation of closed loop breathing apparatuses. This is probably true because until now training procedures have employed the apparatus itself. With the significant risk of injury that inherently accompanies dealing in an oxygen rich atmosphere and the caustic chemicals that are used to emit oxygen in a closed loop system, in addition to the substantial expense that results when numerous training sessions are undertaken, the use of operational equipment is undesirable, however. Inversely, it is desirable to simulate operation for training.
Oxygen breathing apparatuses (OBA's) for the most part are closed loop systems which are not vented except by a relief valve. Other apparatuses are filtering arrangements that often include chemical bags for removing a substantial segment of the irritants out of the air. OBA's were the application for which the present invention was originated. The techniques disclosed, however, have application to the filtering apparatuses too.
The present invention was originally designed for use in conjunction with the commonly used military OBA that is designated the Type A-3. It produces its own oxygen and enables the wearer to enter compartments, voids or tanks which contain smoke, dust or fire, or which have low oxygen supply. The Type A-3 is shown in the drawings, identified as Prior Art. The modifications of the OBA which are indicative of the present invention are shown in FIG. 1. The Type A-3 has a facepiece section that houses the eyepieces, the speaking diaphragm, and head straps. The speaking diaphragm permits the wearer to talk to others and to use communication equipment, such as sound powered phones. The inverted T-tube couples the facepiece to the breathing bag assembly and uses three valves to control the flow of air to and from the facepiece. Two of the valves are flapper type check valves, one each on the input and output sides of the tube, and the other is a vent valve for partially deflating the breathing bag if breathing becomes difficult due to overinflation. The breathing tubes and bags store and supply air to and from the facepiece via the T-tube. The air flow path is shown by the arrows. Dash lines with arrows follow exhaled breath through the canister into the right side of the breathing bag, then to the left side of the breathing bag where the solid line with arrows traces the flow of fresh air through the inhalation process. Exhaled air is recharged by the potassium super oxide contained in the replaceable canister and recirculated to inflate the bag and supply fresh air to the facepiece. Rising upward from the bottom of the canister, the exhaled air is cleansed of its carbon dioxide by the chemical and takes on fresh oxygen. To keep the eyeglasses of the facepeice from fogging, the circulating air is directed past the eyepieces before it reaches the mouth. The breathing bag tubes are long to both support the bags, preventing their complete collapse, and cool the air which becomes quite warm in the canister, before it reaches the wearer.
The initial supply of oxygen is provided by a chlorate candle that is activated by withdrawing a lanyard once the canister is firmly sealed in place. The candle is soon extinguished, but by then the operator's respiration insures that oxygen will continue to be generated.
The present invention permits the original equipment to be used, slightly modified, to preserve realistic fit, feel and operation for training in both the use and the procedures for using the equipment. Equally important, the present invention does not restrict the training to a particular setting but permits it to be rendered on board ship, for example, where the actual emergency might occur. Along with the simulation in the equipment, it is expected that most of the conditions of the emergency would be simulated too. For example, "smoke" or "toxic fumes" would likely be a relatively harmless chemical cloud, as insurance for the safety of the personnel and for simplicity and controllability. The "emergency" is a training procedure, after all, designed to prevent injury or minimize damage, not cause them.